1. Field of the Invention
The present invention relates to a pixel with a short charge transfer time, a forming method thereof, an imaging device and an image forming method by which an image with a wide dynamic range can be formed.
2. Background Art
Conventionally, a relationship between a shape of a photodiode region of a pixel and charge transfer time has not been clear. A conventional pixel is described in Patent Document 1, for example.
Methods for forming a pixel with a wide dynamic range include that in which non-linearity of a semiconductor element is used (for example, Patent Document 2) and that in which images of different periods of exposure time are combined (for example, Non-Patent Document 1). However, in the method in which non-linearity of a semiconductor element is used, the non-linearity is affected by temperature and in some cases correction for temperature is not easy. Further, in the method in which images of different periods of exposure time are combined, images picked up at different time points and therefore an image of a moving object can hardly be formed with a high accuracy.
Thus, conventionally, a pixel in which a shape of the photodiode region is determined in such a way+that a charge transfer time is reduced has not been developed. Further, an imaging device and an image forming method by which an image of a moving object with a wide dynamic range can be formed with a high accuracy have not been developed.